1. Field of the Invention
The present invention relates to a damping device arranged in a gas passage for damping compression waves transmitted from a vibration source by a gas in the gas passage, and a suction structure of a compressor having such a damping device incorporated wherein.
2. Description of the Related Art
Conventionally, a compressor of this type is coupled to an external coolant circuit to constitute a refrigerating circuit, and the suction chamber in the compressor is connected to an evaporator arranged on the downstream region of the external coolant circuit through a pipe. In the housing of the compressor, the suction chamber communicates with each cylinder bore through a suction port, and a suction valve (reed valve) is arranged at a position facing the suction port. The suction valve is arranged to come into contact with a retaining portion recessed in the surrounding wall of the cylinder bore.
In the case where the stroke of the piston is greater and the amount of the sucked gas is greater, the suction valve comes into contact with the retaining portion when the piston moves from the top dead center toward the bottom dead center. In the case where the stroke of the piston is smaller and the amount of the sucked gas is smaller, on the other hand, the suction valve does not sufficiently open to come into contact with the retaining portion when the piston moves from the top dead center toward the bottom dead center, and is subjected to self-excited vibration in an unstable floated state. The self-excited vibration of the suction valve generates compression waves, which are propagated to the evaporator as suction pulsations through a pipe from the suction chamber in the refrigerant gas as a medium.
As a result, the evaporator is vibrated by the suction pulsations propagated from the compressor through the pipe. The evaporator is located in the immediate vicinity of the air outlet of the air-conditioner of the automotive cabin, and therefore a large evaporator vibration causes noise.
The present invention has been developed in view of the aforementioned problem, and the object of the present invention is to provide a damping device and a suction structure of a compressor capable of reducing the propagation of the pulsations by damping compression waves propagated from a vibration source in the gas passage, and thus being capable of improving the damping efficiency.
The present invention provides a damping device arranged in a gas passage for damping compression waves transmitted from a vibration source by a gas in the gas passage. The damping device comprises at least one passage component, which comprises a first cylindrical wall defining a first passage portion therein, a second cylindrical wall arranged outside and parallel to the first cylindrical wall, the first and second cylindrical walls defining a second passage portion between them, a closure wall closing one end of the second passage portion, and a third passage portion arranged near the closure wall and connecting the first passage portion to the second passage portion. One of the first and second passage portions is located on the upstream side of the other of the first and second passage portions with respect to the transmitting direction of compression waves from the vibration source, and a cross-sectional area of the other passage portion is greater than a cross-sectional area of the one passage portion.
According to this configuration, in the damping device arranged in the gas passage, the cross-sectional area of the passage portions increases progressively toward the downstream side of transmission of the compression waves from the vibration source, and therefore a muffler effect is realized to thereby reduce the strength of the compression waves propagated from the vibration source. Also, in view of the fact that the second passage portion between the first and second cylindrical walls communicates with the first passage portion through the third passage portion in the vicinity of the closure wall, a path is formed with foldbacks changing the gas flow direction. As a result, the compression waves are scattered by impinging against the wall in the bent portions of the gas passage, and thus are further damped.
Preferably, the at least one passage component comprises two passage components, one of the two passage components comprising the first cylindrical wall, the second cylindrical wall, the closure wall, and the third passage portion, the other of the two passage components comprising the first cylindrical wall, the second cylindrical wall, the closure wall, and the third passage portion, and the second cylindrical wall of the one passage component and the first cylindrical wall of the other passage component being a common cylindrical wall, the closure wall of the one passage component being arranged at one end of the common cylindrical wall, the closure wall of the other passage component being arranged at the opposite end of the common cylindrical wall.
Preferably, the at least one passage component comprises two or more passage components, which are constituted by three or more concentric cylindrical walls, the closure wall of one of the passage components being arranged at one end of the intermediate cylindrical wall, the closure wall of another passage component being arranged at the opposite end of the intermediate cylindrical wall.
With this configuration, the passage components of the gas passage are coupled in such a manner as to form a route with direction changes, thereby increasing the numbers of direction changes and increasing the whole length of the gas passage. Thus, the effect of damping the compression waves is further improved. Therefore, it is possible to reduce the noise which is transmitted to the other location by the gas passage.
The present invention further provides a compressor having a damping device having a similar feature to that described above. That is, the compressor comprises a housing having at least one compression chamber, a suction chamber, and a discharge chamber, a compression mechanism including a drive shaft and members movable with the drive shaft to cause a gas to be sucked from the suction chamber, compressed in the compression chamber, and discharged into the discharge chamber, a valve device arranged between the suction chamber and the compression chambers, a gas passage connected to the suction chamber, and a damping device arranged in the gas passage for damping compression waves transmitted from a vibration source by a gas in the gas passage. The damping device has a construction similar to that of the above described damping device.
With this configuration, the compression waves generated by vibration sources in the compressor such as suction valves is damped, and the noise transmitted to another location, such as an evaporator of a refrigerating circuit, can be reduced.
Preferably, the damping device is incorporated in the housing of the compressor. Therefore, a compact compressor can be obtained.
Preferably, the housing of the compressor has a damper hole having a side cylindrical wall and a bottom wall, the bottom wall having a fitting hole extending to the suction chamber; the damping device comprising a damper arranged in the damper hole, the damper having an inner cylindrical wall, an outer cylindrical wall arranged outside and parallel to the inner cylindrical wall, an end wall, and at least one radial hole arranged through the inner cylindrical wall near the end wall; the inner cylindrical wall being fitted in the fitting hole for fluid communication with the suction chamber, the outer cylindrical wall being arranged in the damper hole and having one end attached to the end wall and the opposite end spaced apart from the bottom wall; the at least one passage component comprising two passage components, one of the two passage components comprising the inner cylindrical wall acting as the first cylindrical wall, the outer cylindrical wall acting as the second cylindrical wall, the end wall acting as the closure wall, and the at least one radial hole acting as the third passage portion; the other of the two passage components comprising the outer cylindrical wall acting as the first cylindrical wall, the side cylindrical wall acting as the second cylindrical wall, the bottom wall acting as the closure wall, and a space between the opposite end of the outer cylindrical wall and the bottom wall acting as the third passage portion; and the second cylindrical wall of the one passage component and the first cylindrical wall of the other passage component being a common cylindrical wall, the closure wall of the one passage component being arranged at one end of the common cylindrical wall, the closure wall of the other passage component being arranged at the opposite end of the common cylindrical wall.
In this way, the damping device can be constituted in part by the damper, and in part by the walls of the damper hole. Therefore, the damper can be made simple in construction, and the damping device as a whole can establish a higher damping effect.
Preferably, the suction chamber is arranged in the housing at a central region thereof, and the discharge chamber is arranged in the housing at a peripheral region thereof about the suction chamber, the inner cylindrical wall extending through the discharge chamber and reaching the suction chamber. The compressor has a plurality of compression chambers, and the inner cylindrical wall has an inner end located at the center of the suction chamber. Therefore, the gas can be smoothly and uniformly sucked into the respective compression chambers.
According to this configuration, the compression waves propagated to the evaporator are damped and, therefore, the vibration of the evaporator is reduced.